Pump Out Plug Barrier

ABSTRACT

A barrier assembly for a wellbore is disclosed. The barrier assembly includes a housing, a shroud in the housing, and a plug in the shroud. The shroud and plug are made of a dissolvable material that will establish a fluid barrier until such time as the shroud and/or plug dissolves thereby releasing from the housing. The plug is held to the shroud with a shear screw which is susceptible to shearing with application of sufficient pressure to terminate the fluid barrier before the plug and/or shroud dissolves.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 63/180,167 filed Apr. 27, 2021 entitled “DOWNHOLE ASSEMBLY WITH DISSOLVING PLUG AND MILL-OUT I.D.” which is incorporated herein by reference in its entirety.

BACKGROUND

Oil and gas operations in both on shore and offshore locations requires maintaining proper separation of regions, fluids, and pressures at precise times. Wellbores are difficult to access, rendering this seemingly simple task difficult. There are many applications that benefit from proper barriers in the wellbore. Dissolvable materials have enabled removal of barriers in the right conditions without requiring active participation by an operator at the surface. There exists in the industry a continuing need for barriers that perform their tasks for a certain time and that are cost-effective.

SUMMARY

Embodiments of the present disclosure are directed to a barrier assembly including a generally cylindrical housing having an interior bore through the housing, a small inner diameter region in the interior bore defining a narrowest portion of the housing, and a shoulder transverse to an axis of the housing, the axis being generally parallel with the generally cylindrical housing. The barrier assembly also includes a barrier unit receptacle defined by the shoulder and the housing, and a barrier unit. The barrier unit includes a shroud having a generally cylindrical main body defining a central bore through the shroud. The shroud is carried by the barrier unit receptacle. The barrier unit also includes a plug having a generally cylindrical body and a head. The generally cylindrical main body is axially coextensive with the shroud and is located within the central bore through the shroud. The head protrudes from the central bore through the shroud. The shroud is secured to the housing, and the plug is secured to the shroud. One or more of the shroud and the plug is made of a dissolvable material.

Further embodiments of the present disclosure are directed to a method including providing a barrier assembly in a wellbore that includes a housing having a primary axis and a passageway therethrough and being generally aligned with the primary axis. The passageway has a shoulder that is transverse to the primary axis. The barrier assembly also includes a shroud in the housing contacting the shoulder. The shroud has a central bore and a plug in the central bore of the shroud. The plug has a head that protrudes from the shroud at a lower end. The shroud and plug are dissolvable. The method also includes positioning the barrier assembly in the wellbore where the shroud and plug form a fluid barrier that persists until the shroud and/or plug dissolves sufficiently to release from the housing.

Still further embodiments of the present disclosure are directed to a system for establishing a barrier in a wellbore. The system includes a plug having a generally cylindrical body and a head, and the head is wider than the body. The system also includes a shroud around the body of the plug with the head protruding from the shroud. At least one of the plug and shroud is made of a dissolvable material. The system also includes a housing having a passageway through the housing having a narrowest region and a shoulder below the narrowest region, the housing having a shoulder configured to receive the shroud. The housing is located in the wellbore to establish a fluid barrier using the shroud and plug. When the dissolvable material dissolves the fluid barrier is terminated. Various other features of the present disclosure are described below.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a half-cross-section view of a pump out plug barrier assembly according to embodiments of the present disclosure.

FIG. 2 is a cross-sectional view of the shroud of the barrier assembly according to embodiments of the present disclosure.

FIG. 3 is a cross-sectional view of the plug according to embodiments of the present disclosure.

FIG. 4 is a cross-sectional view of the shroud and the plug together according to embodiments of the present disclosure.

FIG. 5 is a cross-sectional view of a barrier assembly having a catcher according to embodiments of the present disclosure.

FIG. 6 is a top view of the catcher according to embodiments of the present disclosure.

FIG. 7 is a cross-sectional view of a barrier assembly according to further embodiments of the present disclosure in which a pump is below the barrier assembly.

FIG. 8 is a cross-sectional view of a barrier assembly according to further embodiments of the present disclosure in which a packer is deployed along with the barrier assembly according to embodiments of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 is a half-cross-section view of a pump out plug barrier assembly 100 according to embodiments of the present disclosure. The right-hand side of FIG. 1 is in cross-section, and the left-hand side shows the outer features of the barrier assembly 100. The barrier assembly 100 can be used in a wellbore at many locations and for many different applications. The barrier assembly 100 can separate regions, fluids, and pressures in the wellbore. Portions of the barrier assembly 100 are made of a dissolvable material that maintains its structural integrity until a certain time at which point the dissolvable material begins to dissolve, rendering the barrier assembly 100 unable to separate the regions, fluids, and pressures. This is by design. The barrier assembly 100 can be used in concert with one or more other items of equipment such as pumps and packers. The separation provided by the barrier assembly 100 benefits this other equipment.

The barrier assembly 100 includes a housing 102 that is a generally cylindrical member having a cylindrical outer surface and a central bore. The housing 102 defines a central axis running through the housing 102. The housing 102 has an outer diameter 104 that is a suitable size to fit into the wellbore. The housing 102 has a small inner diameter 106 that defines the narrowest point through the housing 102. The dimensions of the barrier assembly 100 and its various components can vary for a given installation. The small inner diameter 106 is small only in the sense that it is the narrowest path through the housing 102. The barrier assembly 100 and indeed the small inner diameter 106 may be as large as necessary and suitable. The housing 102 also includes a seat 108 above the small inner diameter 106. The seat 108 can be used with a ball (not shown) such as a frac ball that can be pumped down to the barrier assembly 100 after installation, or the barrier assembly 100 can be run in hole with the ball in place. Above the seat 108 are inner threads 110 that can provide an attachment mechanism for a tool that runs the barrier assembly 100 into the hole.

At a region below the small inner diameter 106 is a shoulder 114 that defines a larger diameter region at a lower portion of the housing 102 that receives a shroud 120 and a plug 140. The shroud 120 and plug 140 together are referred to as a barrier unit. The shroud 120, plug 140, and barrier unit will be described in greater detail below. The larger diameter region at the lower portion of the housing 102 is a barrier unit receptacle 119. The housing 102 also includes outer threads 116 that may be used to attach the barrier assembly 100 to a tubular or other structure in the wellbore. The housing 102 also has a set screw 118 that penetrates horizontally through the housing 102 and into the shroud 120 to at least temporarily hold the shroud 120 in place relative to the housing 102. The housing 102 is made of steel or any other suitable non-dissolvable material and as such will persist in the wellbore after other components may have dissolved. In some embodiments the housing 102 can also be made of a dissolvable material.

FIG. 2 is a cross-sectional view of the shroud 120 of the barrier assembly 100 according to embodiments of the present disclosure. The shroud 120 is a generally cylindrical member having a main body 122 with a central bore 124 passing through vertically generally along the axis of the barrier. Tha main body 122 has recesses 126 for receiving a seal such as an O-ring or other suitable seal that will create a seal between the shroud 120 and the housing 102. There may be any number of recesses 126. More if a more robust seal is needed, and fewer recesses 126 if lower pressures or a less harsh environment is expected. The shroud 120 also has a shear screw hole 128 passing horizontally through the main body 122, and a set screw hole 130 that passes partway into the main body 122 but does not reach the central bore 124. The shear screw hole 128 may be a through hole, providing access from outside the shroud 120 to the central bore 124. In the shown embodiments there are two such shear screw holes 128; however, more, or fewer such holes may be present as needed.

FIG. 3 is a cross-sectional view of the plug 140 according to embodiments of the present disclosure. The plug 140 is a generally cylindrical member having a main body 142 that is sized to fit within the central bore 124 of the shroud 120. The plug 140 also has a head 146 at a lower portion that protrudes from the shroud 120 and contacts a bottom surface of the shroud 120. The plug 140 also has recesses 144 for receiving a seal such as an O-ring to provide a seal between the plug 140 and the shroud 120. The plug 140 further includes a shear screw 148 that is aligned with the shear screw hole 128 in the shroud 120.

FIG. 4 is a cross-sectional view of the shroud 120 and the plug 140 together according to embodiments of the present disclosure. Features of the shroud 120 and plug 140 are shown. Shear screws 152 are shown in the shear screw holes 148 in the plug 140 and the shear screw holes 128 in the shroud 120. A set screw 154 is shown in the set screw hole 130 (see FIG. 2 ) of the main body 122 of the shroud 120. The set screw 154 fits into the housing as shown in FIG. 1 . Seals 150 are shown between the plug 140 and the shroud 120.

Each of the shroud 120 and plug 140 may be made of a dissolvable material such as a magnesium-based material. Any suitable dissolvable material may be used, provided the material has the desired strength and dissolution rates for a given application. In some embodiments one of the plug 140 and shroud 120 is dissolvable and the other is not. The barrier assembly 100 therefore can be run in hole and will provide separation between a region above the barrier assembly 100 and below for a desired time based on the material characteristics and then the plug 140 and/or shroud 120 dissolves. Once the plug 140 and/or shroud 120 dissolve the barrier assembly 100 ceases to function as a barrier and instead allows fluid communication through the barrier assembly 100.

In some embodiments the shear screws 152 are shearable with sufficient pressure above or below the barrier assembly 100. The pressure may be intentionally applied with a pump at a desired time that will break the shear screws 152 leaving the plug 140 unatttached, thereby allowing fluid through the barrier assembly 100 without having to wait for full dissolution of the plug 140 and/or shroud 120. Even after the plug 140 is released the shroud 120 and/or plug 140 will dissolve, rendering the effective diameter of the barrier assembly 100 larger than immediately after releasing the plug 140.

FIG. 5 is a cross-sectional view of a barrier assembly 160 having a catcher 162 according to embodiments of the present disclosure. FIG. 6 is a top view of the catcher 162 according to embodiments of the present disclosure. Referring to FIGS. 5 and 6 together, the barier 160 is substantially similar to the barrier assembly 100 shown in FIGS. 1-4 . The barrier assembly 160 includes a mandrel 161 that is attached to the housing 102 at a lower extent of the housing 102. The mandrel 161 can be a cylindrical member extending downward from the housing 102. A catcher 162 is coupled to the mandrel 161 away from the shroud 120 and plug 140. The distance between the catcher 162 and plug 140 and shroud 120 can be sufficient to allow the plug 140 and any screw or portion thereof to release from the barrier assembly 160 and come to rest on the catcher 162. The catcher 162 has holes 164 that permit fluid to flow through the holes 164 while preventing the plug 140 to fit through the holes 164. The catcher 162 can have any number of holes 164 in any configuration to allow fluid through and prevent the plug 140 from dropping until such time as the plug 140 dissolves and no longer represents a blockage risk and can then pass through the holes 164. The catcher 162 can also catch portions of the shroud 120 in embodiments in which the shroud 120 is also dissolvable.

In other embodiments the catcher 162 is not directly coupled to the barrier assembly 160 and can instead be found as part of another piece of equipment in the wellbore located in a position to operate the same way as shown and described in FIGS. 5 and 6 . In some embodiments the catcher 162 itself is dissolvable. The catcher 162 may have a dissolution rate that is slower than that of the plug 140 and/or shroud 120 such that the catcher 162 holds the plug 140 and/or shroud 120 until they are dissolved sufficiently, and only then dissolves itself. In some embodiments the mandrel 161 can also be dissolvable.

FIG. 7 is a cross-sectional view of a barrier assembly 170 according to further embodiments of the present disclosure in which a pump 170 is below the barrier assembly 170. The barrier assembly 170 can be substantially similar to those previously described and can include a mandrel 161. In this embodiment in the place of a catcher is a pump 170 such as an electronic submersible pump (“ESP”) or a progressive cavity pump (“PCP”). The pump 170 is shown here without obscuring the subject disclosure with unnecessary details of the pump 170 and it is to be appreciated that any sort of pump can be used with the barrier assembly 170. The barrier assembly 170 can operate to prevent fluid from reaching the pump 170 until such time as the pump 170 is in the appropriate position and has sufficient power and fluids provided to it. Then the barrier assembly 170 can be released via pressure or by dissolution of the shroud 120 and/or plug 140 at which point the pump 170 can be operated.

In other embodiments the pump 170 can be in the wellbore separate from the barrier assembly 170, but other than that difference can operate as described with respect to FIG. 7 in which embodiment the pump 170 is attached to the barrier assembly 170. In other embodiments the pump 170 can have a catcher (not shown) attached that catches the released plug 140 and fragments thereof.

FIG. 8 is a cross-sectional view of a barrier assembly 180 according to further embodiments of the present disclosure in which a packer 174 is deployed along with the barrier assembly 180 according to embodiments of the present disclosure. The barrier assembly 180 includes features similar to those in other barriers shown and described herein. In the depicted embodiment the barrier assembly 180 has a mandrel 161 attached to the housing 102 at an upper region of the housing 102. A packer 174 can be coupled to the mandrel 161 while the barrier assembly 180 is run in hole. The barrier assembly 180 can prevent fluid from reaching the packer 174 until the packer 174 can be set. Once the packer 174 is set the barrier assembly 180 can release and the packer 174 assumes the role of barrier in the well.

The foregoing disclosure hereby enables a person of ordinary skill in the art to make and use the disclosed systems without undue experimentation. Certain examples are given to for purposes of explanation and are not given in a limiting manner. 

1. A barrier assembly, comprising: a generally cylindrical housing having: an interior bore through the housing; a small inner diameter region in the interior bore defining a narrowest portion of the housing; a shoulder transverse to an axis of the housing, the axis being generally parallel with the generally cylindrical housing; and a barrier unit receptacle defined by the shoulder and the housing; and a barrier unit comprising: a shroud having a generally cylindrical main body defining a central bore through the shroud, wherein the shroud is carried by the barrier unit receptacle; and a plug having a generally cylindrical body and a head, wherein the generally cylindrical main body is axially coextensive with the shroud and is located within the central bore through the shroud, wherein the head protrudes from the central bore through the shroud, wherein the shroud is secured to the housing, wherein the plug is secured to the shroud, and wherein one or more of the shroud and the plug is made of a dissolvable material.
 2. The barrier assembly of claim 1, further comprising: a mandrel coupled to the housing; a pump coupled to the mandrel, wherein the barrier unit forms a fluid barrier that prevents fluid from reaching the pump through the barrier unit.
 3. The barrier assembly of claim 1, further comprising: a mandrel coupled to the housing; a packer coupled to the mandrel, wherein the barrier unit forms a fluid barrier that prevents fluid from reaching the packer through the barrier unit.
 4. The barrier assembly of claim 1, wherein the shroud is coupled to the housing via a set screw.
 5. The barrier assembly of claim 1, wherein the plug is coupled to the shroud via a shear screw.
 6. The barrier assembly of claim 5 wherein the shear screw is shearable via pressure application upon the barrier unit through the housing.
 7. The barrier assembly of claim 1, further comprising one or more seals between the shroud and the housing.
 8. The barrier assembly of claim 1, further comprising one or more seals between the plug and the shroud.
 9. The barrier assembly of claim 1, further comprising a catcher below the barrier assembly configured to permit fluid to pass through the catcher and to prevent the plug and/or shroud from passing through the catcher.
 10. A method, comprising: providing a barrier assembly in a wellbore, the barrier assembly comprising: a housing having a primary axis and a passageway therethrough and being generally aligned with the primary axis, wherein the passageway has a shoulder that is transverse to the primary axis; a shroud in the housing contacting the shoulder, the shroud having a central bore; a plug in the central bore of the shroud, wherein the plug has a head that protrudes from the shroud at a lower end, and wherein the shroud and plug are dissolvable; and positioning the barrier assembly in the wellbore where the shroud and plug form a fluid barrier that persists until the shroud and/or plug dissolves sufficiently to release from the housing.
 11. The method of claim 10 wherein the shroud is held to the housing via a set screw.
 12. The method of claim 10 wherein the plug is held to the shroud via a shear screw.
 13. The method of claim 12, the method further comprising pressurizing the barrier assembly such that the shear screw is sheared, thereby releasing the plug from the shroud.
 14. The method of claim 10, the barrier assembly further comprising a seal between the shroud and the housing.
 15. The method of claim 10, the barrier assembly further comprising a seal between the plug and the shroud.
 16. The method of claim 10, the barrier assembly further comprising a ball seat in the passageway in the housing above the shoulder.
 17. The method of claim 10, further comprising providing a pump below the barrier assembly, wherein the barrier assembly is configured to prevent fluid from reaching the pump until such time as the shroud and/or plug is released from the housing.
 18. The method of claim 10, further comprising providing a packer above the barrier assembly, wherein the barrier assembly is configured to prevent fluid from reaching the packer until such time as the shroud and/or plug is released from the housing.
 19. A system for establishing a barrier in a wellbore, the system comprising: a plug having a generally cylindrical body and a head, the head being wider than the body; a shroud around the body of the plug with the head protruding from the shroud, wherein at least one of the plug and shroud is made of a dissolvable material; a housing having a passageway through the housing having a narrowest region and a shoulder below the narrowest region, the housing having a shoulder configured to receive the shroud, wherein the housing is located in the wellbore to establish a fluid barrier using the shroud and plug, wherein when the dissolvable material dissolves the fluid barrier is terminated.
 20. The system of claim 19, further comprising: a set screw holding the housing to the shroud; a shear screw holding the shroud to the plug; the plug has a head protruding from the shroud at a lower end of the shroud; a first seal between the shroud and the housing; and a second seal between the plug and the shroud. 